[vserver] Problem with host process ending up to be child of guest process

From: Fiedler Roman <Roman.Fiedler_at_ait.ac.at>
Date: Mon 13 Oct 2014 - 09:52:36 BST
Message-ID: <2ECE9D9EEF1F524185270138AE23265947D128DA@S0MSMAIL111.arc.local>

Hello List,

Analyzing a problem today, It seems the the root cause is, that a host
process ended up being the child of a guest process after using "vserver
exec". Since the guest process is in the guest's PID namespace, tools on the
host fail to react accordingly, e.g. bash job-control gets stuck or
start-stop-daemon reacts unexpected.

Some questions to that:

* Can someone give a hint, how this could happen, thus being able to attempt
to fix the problem for now using a workaround?
* Is this caused by known behavior of vserver exec and misuse from my side?
* No matter if misuse or bug, should this case be prevented since it should
also cause security risks? A host process uses the parent pid of itself or
another host process, but parent pid is from guest namespace. So from my
understanding it could collide with PIDs from host namespace, thus host
process might operate on arbitrary other host process, e.g. signalling or
modifying it or just like with bash, getting stuck running wait(-1) in
endless loop?


Received on Mon Oct 13 09:52:50 2014
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